Chaeles dear



UNITED STATES PATENT OFFICE.

CHARLES DEAR, OF LONDON, ENGLAND, ASSIGNOR TO THE MIRIS STEEL COMPANY LIMITED, OF LONDON, ENGLAND.

MANUFACTURE OF STEEL.

Ho Drawing.

To all whom it may (U/MOTH.

lie it known that l, (hinatns lhmn, a subject of the King of l lngland, residing in London, England, have invented certain new and useful lniprovements in the Manufacture of Steel, oi which the following is a specification.

lhis invention relates to that procedure in the manufacture of steel by which the steel is immersed hot in a bath of liquid with a view to improving the constitution of the steel by means of the reactions taking place between it and the materials in the bath.

i\ccordiug to the present invention the liquid for a bath of the kind described volituius nitric a: id, sulfuric or alternatively -uli'urous arid and an ammonium compound. such for example as ammonium hydrate or ammonium chlorid. If desired the two sulfur 11/. ids may both be used. The preferred composition of bath is one in which ammonium hydrate is employed, whether alone or in con unction with ammonium chlorid or some other ammonium compound.

The bath is most effectual if the steel is immersed in it at a temperature of not less than about 800 C. at its outer surface.

The proportions in which the said materials are employed are preferably those of the following weights of each added to each thousand gallons of Water, namely 2 cwt. of sulfuric or sulfurous acid; 3 ewt. of nitric mid; 2% cwt. of sal-ammoniac. Or I may use 1 cwt. of sulfuric and 1 cwt. of sulfurous acid instead of 200 cwt. of sulfuricor sulfurous acid. It is preferred, further, to add 2;} cwt. of strongest liquid ammonia to each thousand gallons of water. After repeated use this last ingredient should be added to restore vigor of operation to the bath and in proportion as this is added so should also the nitric, sulfuric or sulfurous acid be added maintaining the aforestated proportions, that is to say, two and three parts, by Weight respectively of the acids to 21 parts by Weight of the liquid ammonia.

The bath is prepared by dissolving first in the Water such solids as are employed, then addin the liquids, the liquid ammonia being a ded last of all. As the fluid evaporates Water should be added to make good this loss and as the bath loses ammonia this loss also should be made 00d, takin care to add also the other ingre ients if an when Specification of Letters; Patent.

Application filed December 80, 1916.

Patented May 27, 1919.

Serial No. 139,908.

necessary to preserve the constitution of the bath in the proportions stated.

The valuable effects of innnersing steel in this bath are realized to the best of advantage if the steel be plunged in it at a temper ature at which the interior of the mass is still fluid or partly fluid, or if it be not convenient to operate before the temperature has sunk below this value, for want of facilities so to do, then the temperature should be again raised so as to be not less than that at which the interior will he fluid or nearly fluid. ln any case the effe ts are less marked or penetrate to a less depth if the mass has been reduied in area by rolling or otherwise subjected to mechanical working.

The steel should not he removed from the bath except to he put into the soaking pits until recalesceme cannot ocrur in the open air after removal.

Although the hereinbel'ore indicated conditions of use are those which enhance the valuable effects of this invention, the application of this invention is not limited to cases in which the said conditions obtain. The hereinbefore described bath for the immersion of hot steel to change and improve its qualities, other than to harden it by the ordinary process of plunging the steel to cool it suddenly, is a bath within the scope of the present invention, however used.

It has heretofore been proposed to treat steel with gas, fluids, or solids, in order to introduce hydrogen lhereinto and such proc esses have been applied to high carbon and low carbon steel; it has furthermore been proposed to immerse billets or other rolled sections in various liquid compounds.

The general effect of this bath is to enhance the toughness of the steel and its ductility. The process is applicable, with advantageous results to alloy steels, such, for example, as nickel steel.

hat I claim as my invention and desire to secure by Letters Patent is 1. An.aqueous liquid for quenching hot steel to improve its toughness or its ductility which liquid contains nitric acid, a sulfur acid and an ammonium compound.

2. An aqueous liquid for quenching hot steel to improve its toughness or its ductility which liquid has been prepared by mixing nitric acid, sulfuric or sulfurous acid, an ammonium compound and Water.

3. An aqueous liquid for quenching hot steel to improve its toughness or its ductility Which liquid contains nitric acid, a sulfur acid and an ammonium compound in the proportions of 3 cwt. oi' the nitric acid, 2 cwt. of sulfur acid and 2% cwt. of ammonium ehlorid to every 1000 gallons of water.

4 The method of treating steel comprising the step of placing a piece of hot steel in a bath containing nitric acid, sulfur acid and an ammonium compound.

5. The method of treating steel comprising the step of plunging a piece of steel in which the interior is still molten into a bath containing nitric acid, sulfur acid and an ammonium compound.

6. The method of treating steel comprising the step of plunging a piece of steel in which the interior is still molten into a bath containing nitric acid, sulfuric acid and an ammonium compound.

7. The method of treating steel comprising the step of providing a bath containing 3 cwt. of nitric acid, 2 cwt. of sulfur acid, and 21} cWt. of ammonium chlorid to every 1000 gallons of Water, and plunging a piece of hot steel in said bath and retaining it therein until it has become cold beyond the point where recalescence cannot occur in the open air after removal.

8. The method of treating steel comprising the step of providing a bath containing 3 cwt. of nitric acid, 2 cwt. of sulfur acid, and 2% cwt. of amn'ionium chlorid to every 1000 gallons of water, and plunging a piece of steel which has been heated to a tempera ture of 800 G. into said bath and retaining it therein until it has become cold beyond the point where reealescence cannot occur in the open air after removal.

In testimony whereof I have signed my name to this specification.

CHARLES DEAR.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). C. 

